This invention relates to a magnetic recording/reproducing apparatus which uses a cassette and is able to select a desired tune or message by passing over one or several tunes or messages during rewind or fast-feed.
A mechanism which selects a desired tune by fast-feeding or rewinding the magnetic tape is known. In this prior art mechanism, however, a movable plate carrying a magnetic head is attracted and is held against the strong force of spring while the desired tune is being played, so that an electromagnetic locking device with high consumption of electric power is required.
An example of an apparatus of this kind will now be described in conjunction with FIG. 1 of the appended drawings.
As shown, a magnetic coil 123a is wound around a cylindrical, soft steel, magnetic core 123 which is planted on a square-shaped york 122 fixed to a frame (not shown). There is a closed magnetic circuit through the york 122 and the magnetic core 123. A soft steel member 121 rotatably supported on the frame by a shaft 121-1 is strongly attracted and locked when the member 121 moves to the position shown by dotted line K. For example, the soft steel member 121 is biased in the direction of arrow H by a spring (not shown) and in the direction of the bias an abutting pin 121b fixed to a lever 121a engages a free end of the member 121. When the lever 121a is manually pushed in the direction of arrow J, the member 121 is rotated clockwise to the position of the dotted line K where it is attracted and held by the magnetic core 123. In this way the lever is locked in place and prevented from returning to the position shown in FIG. 1. The end portions of the york 122 and the magnetic core 123 are in contact with a surface of the soft steel member 121 with substantially no clearance therebetween so that the magnetic circuit is closed and the member 121 is held.
In this prior art apparatus, however, there is a drawback of the efficiency being low when the magnetic circuit is closed because of the leakage of magnetic flux at several portions. Another drawback in the prior art is that the contact-force is extremely decreased and causes disadvantages if there is dust on the contact surfaces. Another disadvantage of the apparatus in the prior art is that it is expensive and not available for mass-production because of the need for high relative-accuracy of each portion during assembly. Furthermore, since the lever 121a is to move in the direction of arrow J there are additional disadvantages depending on the usage. It is desirable that no forces act on the soft steel member 121 before it comes in contact with the magnetic core 123 and that a strong locking force occurs only when contact is made, a feature not found in the prior art.